A quick and dirty way is to use "wget" or another file transfer program like ftp to download a large file (at least several megabytes) from a remote server. Check out the bytes/sec reported. Try it at various times throughout the day to get an average. Alternately, you could use something like <A HREF="http://freshmeat.net/projects/bing/">Bing</A>. Search www.freshmeat.net for other possibilities.